aabb-2d/index.js

2d axis aligned bounding boxes

module.exports = AABB

var vec2 = require('gl-matrix').vec2

function AABB(pos, vec) {
  if(!(this instanceof AABB)) {
    return new AABB(pos, vec)
  }

  this.base = pos
  this.vec = vec

  this.mag = vec2.length(this.vec)

  this.max = vec2.create()
  vec2.add(this.max, this.base, this.vec)
}

var cons = AABB
  , proto = cons.prototype

proto.perimeter = function() {
  return 2 * (this.vec[0] + this.vec[1])
}

proto.area = function() {
  return this.vec[0] * this.vec[0] + this.vec[1] * this.vec[1]
}

proto.intperimeter = function() {
  return (this.vec[0] + this.vec[1]) << 1
}

proto.width = function() {
  return this.vec[0]
}

proto.height = function() {
  return this.vec[1]
}

proto.x0 = function() {
  return this.base[0]
}

proto.y0 = function() {
  return this.base[1]
}

proto.x1 = function() {
  return this.max[0]
}

proto.y1 = function() {
  return this.max[1]
}

proto.translate = function(by) {
  vec2.add(this.max, this.max, by)
  vec2.add(this.base, this.base, by)
  return this
}

proto.expand = function(aabb) {
  var max = vec2.create()
    , min = vec2.create()

  vec2.max(max, aabb.max, this.max)
  vec2.min(min, aabb.base, this.base)
  vec2.sub(max, max, min)

  return new AABB(min, max)
}

proto.intersects = function(aabb) {
  if(aabb.base[0] > this.max[0]) return false
  if(aabb.base[1] > this.max[1]) return false
  if(aabb.max[0] < this.base[0]) return false
  if(aabb.max[1] < this.base[1]) return false

  return true
}

proto.union = function(aabb) {
  if(!this.intersects(aabb)) return null

  var base_x = Math.max(aabb.base[0], this.base[0])
    , base_y = Math.max(aabb.base[1], this.base[1])
    , max_x = Math.min(aabb.max[0], this.max[0])
    , max_y = Math.min(aabb.max[1], this.max[1])

  return new AABB([base_x, base_y], [max_x - base_x, max_y - base_y])
}